Electric dental furnace.



No 849,335. PATENTED APR. 2, 1907.

L. MARKWITZ.

ELECTRIC DENTAL FURNAGE.

APPLICATION FILED JAILZZ, 1906.

R SHEETS-SHEET l.

wmdde:

. M FLMW PATENTED APR. 2, 1907.

L. MABKWITZ. BLEGTRIC DENTAL FURNACE.

APPLICATION FILED JAILZZ, 1906.

3 SHEETSSHE-ET 9 -No. 849,835. PATENTED APR. 2, 1907.

' -L. MARKWITZ.

ELECTRIC DENTAL FURNACE.

APPLICATION FILED 1111.22, 1906.

witnesses:

UNITED STAT-ES PATENT osrion.

LOUIS MARKWITZ, or SAN FRANCISCO, oALiEonnni. v

su-zormc DENTAL FURNACE.

To all whom it may concern.-

Be it known that 1, Louis. MAnKwrrz,a citizen of the United States, anda resident of the city of San Francisco, county of San;

Francisco, and State of California, have in vented a new and usefulImprovement in 'out and then, of course,' requ1res immediate,

repair, and it is therefore desirable'that the arrangement of the partsbesuch that the re pair of the vplatinum wiring can be immediately madewhen necessary, and that it will take but a few minutes. To this end theparts ofv myfurnace are arranged and com ined as illustrated in thedrawings. In the latter, Figure 1. representsa general view inperspective of my furnace. Fig. 2 is a longitudinal section aboutcentrally taken. Fig. 3 is a cross-sectionon a line a; m of Fig. '2.

"Fig. 4 is a'front end perspective of the muflie.

Fig. 5 is a perspective detail of the two-part heat resisting jacket ofthe muffie. -Fig.,,6 is a perspective detail of the outer casing of myfurnace; and Fig. 7 is a to "view or plan of my'furnace, also showing te position of the resistance-coils in broken outline.

The numerals designate the partsreferred to. s a

My furnace comprises an exterior casing, of cast-iron, 1,-consisting oftwo parts. 2 3, (see Fig. 6,) the former including the bottom 4 and thefront wall and the latter includingthe side walls, roof, and back wall6. g It is to be noted that thetwo parts are siegarableand. may befastened together, as' trated" in Fig. 6 and the-sectionalviews, Fig.2and 3.

Whenarranged together, the "side walls. and v the back of the removablepart 3 rest on the bottom 4.

To secure the parts in place, the bottom 4 is provided with a'verticalflange-plate 7 attherear end, having two threaded holes 58, (See '1 Fig.6, which to receive screws 10,-ins'ert ed through corresponding holes 9in the base Specification of Letters Batent. A'oplicationfiled January22, 1906. seam. 297,367.

Po t 16, hich cents, approximately.

made ofivulcaniz'ed rubber, which is; adjust Thfro, t wall" BatentedApril 2, 1907.

i of the rear wall portion 6. The bottom 4 is also made with aprojecting hearth-plate 11 andlegs 12. I 7

Within the outer casing is placed a heatresisting jacket 19, made offire-clay and silex or 0t er suitable material."' Said jacket is made intwo arts 19 19*, so asto be readily separated. ithin the jacket- 19isplaced the mufile 20, also made of-heat-resisting material. On theexterior of'the muffle 20 are provided spirally arranged' grooves 21,

in which is wound the platinum wire 22, one

end of which wire, 22,, is leddownward through grooves'on the rearexterior face of the muflie, as isshown in broken line in Fig. 3. Thecasing 1. rests on aresistance or rheostat box 13, provided with a usualcircuit-switch 14, also a resistance switch 1 .3 to adjust the degree ofresistance. and binding to connect the GiIfCHlt-\ wires. 1

The resistance-box ,is

17 are preferably arranged as shown in Fig. 7, the idea being to leaveample room or space at the center'of box, so as to make it convenient todetach the platinum-wire ends when required. The two ends 22 of theplatinum wire 22 areleddownward from the muffle through aperturesthereforprovided in the encompassingjpa'rt's and are connected with thecoils of'the resistance-box.

From theforegoingflescription the convenience of the arrangement of-myfurnace\ o is now apparent. Incase of aburn-out it is the work of amoment to remove the screws 9 10, liftoff. the upper part 3 of the outercasing, next to lift ofi the'upper. art of the jacket 19, so as toexpose the mu e20, then to re air the wire windings-of the latter,.andfinally to reassemble the parts. This repair can be made in from five tofifteen minutes and at the nominal cost of from. five .to ten To renderthe adjustment of the resist ance swi-tch'15 convenient when desiring tooperate'iwithin' i afl'predetermined j degree of resistance, Iflprovldearemovable', tip 26,

. 5 able 'to any convenient point of the resist ance-switch,

The -'cirouit-switch 14 is preferably placed on the left side, 'asshown,so as to leave a;

space ,elear on the right side on which to my the instruments beingused, I

,rfof. th har s g h s. an-

convenientlyniade Wltll a marble" top, and the resistance-coils openin 5leading into the muffle 20, and the front end of the roof of such outercasing is made with a slot 24,in which to slide a door 25, made of asheet of mica.

I claim 1. In an electric furnace, the combination comprising a m'uflleprovided with corrugations or grooves on its exterior surface arrangedto receive a winding of wire; a jacket of earthy non-heat-conductingmaterial, encompassing said muffle, and made in two separable parts, andan outer metal casing also made of two separable parts, and providedwith means for fastening :the same together; the front wall of saidouter casing being made with an opening leading into the mufile, andprovided with a suitable slidingdoor to close said opening. I

2. In an electric furnace, the combination comprising a muffle providedwith corruga tions or'grooves, on its exterior surface, arranged toreceive a winding of Wire, a jacketof earthy nonheatconductingmateri-al,..cn compassing said muffle and consisting'of twohorizontally-separable parts as 19, '19" and an outer metal casing alsomadcof two sepa-- rable parts, and provided with-means for fastening thesame together; the front wall of said outer casing being made with anopening leading into the vmilfile, and provided with a suitable slidingdoor .to close said opening. 3. In an electric furnace,tl'lGCOIHlJlHfltlOII comprising a muffle provided. with corrugations orgrooves on its exterior surface arranged to receive a winding of wire, ajacket of earthy non-heat-conducting' material, encompassing saidmuffle, and made in two separable parts, an outer metal casing made oftwo integral parts, one consisting of the bottomand the front end Wall,and the other consisting of an arched roof, the side walls and the rearend wall; the frpnt wall being made with an opening leading into themuffle, and provided with a suitable slidingdoor to close said opening;and means for fastening the two parts of the outer casing afterassembling the parts.

4. In an electric furnace, the combination comprising a muffle providedwith corrugations or grooves on its exterior surface ar ranged toreceive a winding of wire, a jacket of eai'tliy non-hea't-conductingmaterial, encompassing said muffle, and made in'two separable parts, anouter metal casing made of two parts, one consisting of the bottom andthe front end wall and, the other consisting of an arched roof, the sidewalls and the rear end Wall, the front wall being made with an openingleading into the muffle, and providedwith a sliding door to close saidopening; aflange-plate on the rear end of the bottom part of such outercasing, and means for locking the rear end wall of the outer casingthereto, to hold the parts together.

5: An electric furnace comprising a muffle provided with corrugations orgrooves on'its exterior surface arranged to receive a wii1ding of wire,a jacket of earthy non-heat-conducting material, encompassing saidmuffle and consisting of two horizontally-separable parts as 19, 19, anouter metal casing made of two parts, one consisting of the' bottom andthe front end Wall, and the other consisting of an arched roof, the sideWalls and .the rear end wall; the front wall being made for locking therear end wall of the outer case consisting of a rheostat or resistancebox, the

coils of which are arranged in groups rear- Ward and forward of thecenter, so as to leave aspace between said groups for the purposespecified; means for adjusting the rheostat, an outer metal casing,mounted on said base, said casing consisting of two parts 2, 3 onecomprising the bottom and the front end wall, the latter being made witha door-opening, and the other part of sai l"casing comprising an archedroof, the side walls, and the rear end wall, the roof portion being madewith a-slot 24; a door of transparent material inserted in said slot toclose the opening of the front wall, means for fastening the two partsof the outer casing together; a muffle provided with corrugations orgrooves on its exterior surface, and having a winding of wire lying insaid grooves electrically connected with the rheostat; and an interme}diate jacket, of earthy non-hea't-conducting material,encompassing saidmuffle and consisting of two separable parts, as 19, 19.

In testimony whereof-I have hereunto affixed my signature in thepresence of. two witnesses.

LOUIS MARKWIT-Z.

